Which of the Following Statements Is True

Which of the following statements is true?

A) When two nations specialize and trade, there is a loss of efficiency and both the nations are made worse off.
B) Trade between two nations is most beneficial when neither has a comparative advantage in the production of any goods and services.
C) Trade between nations allows each nation to specialize in the production of goods for which it has comparative advantage.
D) Trade between two nations is possible only when the opportunity costs of producing goods and services in both nations are identical.